Aripiprazole of formula (1):

or 7-[4-[4-(2,3-Dichlorophenyl)-1-piperazinyl]butoxy]-3,4-dihydro-2(1H)-quinolinone and its salts are useful for treating schizophrenia and their therapeutic uses were disclosed in U.S. Pat. No. 5,006,528.
Processes for the preparation of aripiprazole and its salts were described in U.S. Pat. No. 5,006,528. Various crystalline forms of aripiprazole and its hydrates were disclosed in WO 03/026659, Japanese Unexamined Patent Publication No. 191256/1990 and 4th Japanese-Korean Symposium on Separation Technology (Oct. 6-8, 1996).
We have discovered a novel crystalline form of aripiprazole, aripiprazole methanolate and aripiprazole ethylene dichloride solvate. The novel crystalline form of aripiprazole is non hygroscopic, do not have the tendency to convert to other forms and suitable for pharmaceutical preparations.
The methanolate and ethylene dichloride solvate are non-hygroscopic, obtainable in pure form and can be converted to crystalline forms of aripiprazole and aripiprazole hydrates.
Therefore, the solvates are useful as intermediates for preparing pure aripiprazole or aripiprazole hydrates in any crystalline form.
Thus, one object of the present invention is to provide stable, non-hygroscopic crystalline form of aripiprazole, process for preparing this form and pharmaceutical compositions containing it.
Another object of the present invention is to provide aripiprazole methanolate and aripiprazole ethylenedichloride solvate and process for preparing the solvates; and use of these solvates to prepare other forms of aripiprazole.